1. Field of the Invention
The present invention relates to a laryngoscope, which is a device used in an endotracheal intubation procedure. In particular, this invention is an improved design for the blade of a laryngoscope.
2. Description of the Related Art
While a laryngoscope may be used for inspection of the upper airway for possible foreign body obstruction or to visualize the larynx, the primary purpose of the laryngoscope is to visualize the vocal chords prior to insertion of an endotracheal tube during intubation. The need for such intubation may arise during a controlled situation, such as pre-surgery, or in a crisis situation where the patient is unable to breathe adequately and requires advanced airway interventions.
In order to intubate the patient, the intubator (either a physician or trained technician) must have a clear view of the vocal chords to insure the tube enters between the chords and not down the esophagus. When the body is in the supine position and the head is in the normal anatomic position the airway is narrowed and the tongue itself may possibly become an obstructing factor. It is therefore recommended that the intubator be able to secure the tongue and visualize the vocal chords as rapidly as possible. The laryngoscope itself generally comprises a handle and a blade. The intubator will hold the handle in one hand and position the blade against the patient's tongue. The intubator will use the edge of the blade to push the tongue to one side and the tip of the blade to lift the epiglottis, exposing the vocal chords. The handle will generally contain a light source which will illuminate the vocal chords. The intubator will then use her free hand to insert the tube between the patient's vocal chords.
In the current state of the art, the two most widely used blades as Miller blades and Macintosh blades. A Miller blade is a substantially straight blade with a curved tip, the curve commencing approximately 2 inches from the end of the blade. A Macintosh is a blade which is curved substantially its entire length (U.S. Pat. No. 2,354,471. Issued Jul. 25, 1944). In practice, the Miller blade is inserted along the longitudinal axis of the larynx past the epiglottis to lift it enough to visualize the vocal chords and slip the endotracheal tube between the chords and into the trachea. The Macintosh blade is inserted on a combination of the axis of the oral cavity and the longitudinal axis of the larynx, the tip being placed in the vallecula, which is the shallow depression in the membranous folds of tissue between the epiglottis and the roof of the tongue. By applying upward pressure at the vallecula, the epiglottis is raised enough to visualize the vocal chords.
While both Miller blades and Macintosh blades are adequate for performing intubation, both types of blade designs leaves three problems unsolved. First, prior art blades are designed such that in order to visualize the vocal chords, the doctor or technician will operate the laryngoscope with one hand and intubate the patient with the other hand. Standard blades are designed for right handed people; that is, the blade is operated with the left hand and the intubation is done with the dominant right hand. Left handed people either require different blades or are required to wield the tool in their dominant hand and attempt intubation, which is a delicate procedure, with their non-dominant hand. A second problem with prior art blades is that they do not include adequate means for securing the tongue. The tongue is always wet and tends to slide off the edge of a standard laryngoscope blade. Lastly, and partially as a result of the first two design shortcomings, current state of the art blades do not provide a sufficient view of the field of work (i.e. the vocal chords), because these tools do not provide an adequate angle of address for the vocal chords and allow unsecured portions of the tongue to block the field of view.
While there have been efforts to improve blade design, none of the improvements, taken either singularly or in combination, adequately address the aforementioned problems. Efforts to improve the curvature of the blade are shown in U.S. Pat. No. 5,003,962, issued Apr. 2, 1991 to Choi, and U.S. Pat. No. 5,406,941 issued Apr. 18, 1995 to Roberts. Choi describes a blade having 3 straight segments, the second segment at a 20 degree angle to the first, and the third at a 30 degree angle to the second. The Roberts patent describes a flat, flexible blade, having a cam attached to one side of the blade so the curvature may be adjusted by rotating the cam. U.S. Pat. No. 3,856,001 issued to O.C. Phillips Dec., 24, 1974 describes a Jackson or straight blade having a “U” shaped cross section and a tip similar to the Miller blade, curving about 2 inches from its end.
Efforts to improve the tip are shown in U.S. Pat. No 4,573,451, issued Mar. 4, 1986 to Bauman, and U.S. Pat. No. 5,603,688 issued Feb. 18, 1997 to Upsher. The Bauman patent describes a blade made of plastic or metal, thinning or hinged at the tip, with a push rod and ratchet to change the angle of the tip. Upsher's patent shows a blade having a hollow tube in the side of the tip to prevent the natural curve of the endotracheal tube to leave the field of vision after exiting the hollow tube in the blade.
Efforts to improve the illumination of the larynx and vocal chords are shown in U.S. Pat. No. 3,771,514 issued Nov. 13, 1973 to Huffman, and in U.S. Pat. No. 3,638,644 issued Feb. 1, 1972 to Reick. The Reick patent shows a light bulb in the handle with a plastic light conduit extending through the blade. The Huffman patent shows a one piece handle and blade, the blade having a prism mounted thereon for reflecting and diffusing light.
These inventions leave the three aforementioned problems unsolved.